Air pump

ABSTRACT

An air pump has a body, a piston rod and a handle. The piston rod is movably inserted into the body and has a rod body, a convex ring and a first engaging part. The convex ring is laterally protruded from the rod body and has a retaining surface. The first engaging part is longitudinally mounted on the convex ring. The handle is mounted on the rod body and has a fixation trough, a retaining ring and a second engaging part. The retaining ring abuts against the retaining surface of the convex ring for preventing a relative rotation between the handle and the piston rod. The second engaging part is longitudinally mounted on the inner surface of the fixation trough and is engaged with the first engaging part of the piston rod. Therefore, the air pump increases the stability between the piston rod and the handle.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of the Taiwan patent application No.101201620, filed on Jan. 20, 2012, the disclosure of which isincorporated herein in its entirety by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to an air pump, and more particularly to the airpump having a handle steadily mounted on a piston rod to prevent arelative rotation between the handle and the piston rod.

2. Description of Related Art

With reference to FIG. 6, an air pump comprises a body 50, a piston rod60 and a handle 70. The body 50 has an end surface and a nozzle 51. Thenozzle 51 is mounted on the end surface of the body 50. The piston rod60 has a top end, a bottom end, an outer thread and a piston. The topend of the piston rod 60 is opposite to the bottom end of the piston rod60. The bottom end of the piston rod 60 is movably inserted into thebody 50. The outer thread is formed near the top end of the piston rod60. The piston is mounted on the bottom end of the piston rod 60. Thehandle 70 has a fixation trough 71 and an inner thread. The fixationtrough 71 is formed in the handle 70. The inner thread is formed in thefixation trough 71 and is screwed with the outer thread of the pistonrod 60, such that the handle 70 is mounted on the top end of the pistonrod 60.

The purpose of the handle 70 is to be held easily by a user and toafford inflation of a chamber such as a tire tube by pushing and pullingthe piston rod 60. When the piston rod 60 is pushed and pulled, theforce being pressed on the handle 70 may cause the relative rotationbetween the handle 70 and the piston rod 60, and then the handle 70 iseasily loosened from the piston rod 60. Therefore, users can not holdthe handle 70 steadily and need to reattach the handle 70 with thepiston rod 60. Moreover, the screw force between the handle 70 and thepiston rod 60 is decreased when the air pump is used for a period andalso because the handle 70 frequently loosens and escapes and is thentightly screwed with the piston rod 60, causing the threaded engagementto be worn.

To overcome the shortcomings, the present invention provides an air pumpto obviate the aforementioned problems.

SUMMARY OF THE INVENTION

An objective of the invention is to provide an air pump to prevent arelative rotation between a handle and a piston rod.

The air pump comprises a body, a piston rod and a handle. The body ishollow and has a nozzle. The piston rod is inserted into the body andhas a rod body, a piston, a convex ring and a first engaging part. Therod body has a top end and a bottom end. The bottom end is opposite tothe top end of the rod body and is inserted into the body. The piston ismounted on the bottom end of the rod body. The convex ring is radiallyformed on and protruded from the rod body near the top end of the rodbody and has an outer surface, a bottom surface and a retaining surface.The retaining surface is mounted on the bottom surface of the convexring of the piston rod. The first engaging part is longitudinallymounted on the outer surface of the convex ring of the piston rod. Thehandle is mounted on the top end of the rod body and has a connectingend, a face, a fixation trough, a retaining ring and a second engagingpart. The connecting end is connected to the top end of the rod body.The face is formed on the connecting end of the handle rod. The fixationtrough is formed in the face of the handle and has an inner surface. Theretaining ring is radially protruded from the inner surface of thefixation trough and abuts against the retaining surface of the convexring. The second engaging part is longitudinally mounted on the innersurface of the fixation trough and is engaged with the first engagingpart of the piston rod.

With the engagement between the second engaging part of the handle andthe first engaging part of the piston rod, the relative rotation betweenthe handle and the piston rod is prevented. Therefore, the top end ofthe piston rod is steadily fixed into the fixation trough of the handle.Thus, the handle of the air pump is easily held and pressed in thepumping process of the air pump.

Other objectives, advantages and novel features of the invention willbecome more apparent from the following detailed description when takenin conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side view of a first embodiment of an air pump in accordancewith the present invention;

FIG. 2 is an enlarged exploded perspective view of the air pump in FIG.1;

FIG. 3 is an enlarged cross sectional side view of the air pump in FIG.1;

FIG. 4 is a cross sectional bottom view of the air pump along line 4-4in FIG. 1;

FIG. 5 is an exploded perspective view of a second embodiment of an airpump in accordance with the present invention; and

FIG. 6 is a side view in partial section of an air pump in accordancewith the prior art.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

With reference to FIGS. 1 and 2, an air pump in accordance with thepresent invention comprises a body 10, a piston rod 20 and a handle 30.

The body 10 is hollow and has an end surface and a nozzle 11. The nozzle11 is mounted on the end surface of the body 10.

The piston rod 20 is movably inserted into the body 10. The piston rod20 comprises a rod body, a piston 21, a convex ring 22 and a firstengaging part 23. The rod body has a top end and a bottom end. Thebottom end is opposite to the top end of the rod body and is insertedinto the body 10. The piston 21 is mounted on the bottom end of the rodbody. The convex ring 22 is radially formed on and protruded from therod body near the top end of the rod body. The convex ring 22 has aretaining surface and an outer surface. The retaining surface is formedon a bottom surface of the convex ring 22 of the piston rod 20. Thefirst engaging part 23 is longitudinally mounted on the outer surface ofthe convex ring 22 of the piston rod 20.

The handle 30 is steadily mounted on the top end of the rod body. Thehandle 30 has a connecting end, a face, a fixation trough 31, aretaining ring 32 and a second engaging part 33. The connecting end isconnected to the top end of the rod body. The face is formed on theconnecting end of the handle 30. The fixation trough 31 is formed in theface of the handle 30 and has an inner surface. The retaining ring 32 isradially protruded from the inner surface of the fixation trough 31 andabuts against the retaining surface of the convex ring 22. The secondengaging part 33 is longitudinally mounted on the inner surface of thefixation trough 31 and is engaged with the first engaging part 23 of thepiston rod 20.

With reference to FIG. 3, the retaining ring 32 abuts against theretaining surface of the convex ring 22. With reference to FIG. 4, thesecond engaging part 33 is engaged with the first engaging part 23 ofthe piston rod 20. Further, the handle 30 is a T-shaped handle and has atransverse part 301 and a longitudinal part 302, and the face and thefixation trough 31 of the handle 30 are formed on an end surface of thelongitudinal part 302 of the handle 30. With reference to FIG. 5, thehandle 30A is cylindrical. The face and the fixation trough 31 of thehandle 30A are formed on an end surface of the cylindrical handle 30A.Preferably, the air pump has multiple slip-resistant ribs formed aroundand protruding from the handle 30A.

Furthermore, the first engaging part 23 of the piston rod 20 is aprotruding rib, and the second engaging part 33 of the handle 30 is agroove, and the protruding rib is fixedly inserted into the groove.Alternatively, the first engaging part 23 of the piston rod 20 is agroove and the second engaging part 33 of the handle 30 is a protrudingrib.

To combine the handle 30 with the piston rod 20, the second engagingpart 33 of the handle 30 is aligned with the first engaging part 23 ofthe piston rod 20. The top end of the rod body of the piston rod 20 isthen pressed into the fixation trough 31 of the handle 30, and theconvex ring 22 and the first engaging part 23 are both located in thefixation trough 31 of the handle 30. The retaining ring 32 abuts againstthe retaining surface of the convex ring 22 to prevent the handle 30being detached from the piston rod 20. With the engagement between thesecond engaging part 33 of the handle 30 and the first engaging part 23of the piston rod 20, the relative rotation between the handle 30 andthe piston rod 20 is prevented. Therefore, the air pump in accordancewith the present invention does not have the problem of the decrement ofthe screw force between the handle and the piston rod of the prior arteven when the air pump in accordance with the present invention is usedfor a long period.

Even though numerous characteristics and advantages of the presentinvention have been set forth in the foregoing description, togetherwith details of the structure and function of the invention, thedisclosure is illustrative only. Changes may be made in detail,especially in matters of shape, size, and arrangement of parts withinthe principles of the invention to the full extent indicated by thebroad general meaning of the terms in which the appended claims areexpressed.

What is claimed is:
 1. An air pump comprising: a body being hollow andhaving: an end surface; and a nozzle mounted on the end surface; apiston rod movably inserted into the body and having a rod body having:a top end; and a bottom end opposite to the top end of the rod body andinserted into the body; a piston mounted on the bottom end of the rodbody; a convex ring radially formed on and protruded from the rod bodynear the top end of the rod body, and having: an outer surface; a bottomsurface; a retaining surface formed on the bottom surface of the convexring of the piston rod; and a first engaging part longitudinally mountedon the outer surface of the convex ring of the piston rod; and a handlemounted on the top end of the rod body and having a connecting endconnected to the top end of the rod body; a face formed on theconnecting end of the handle; a fixation trough formed in the face ofthe handle and having an inner surface; a retaining ring radiallyprotruded from the inner surface of the fixation trough and abuttedagainst the retaining surface of the convex ring; and a second engagingpart longitudinally mounted on the inner surface of the fixation troughand engaged with the first engaging part of the piston rod.
 2. The airpump as claimed in claim 1, wherein the first engaging part of thepiston rod is a protruding rib, and the second engaging part of thehandle is a groove whereby the protruding rib is fixedly insertable inthe groove.
 3. The air pump as claimed in claim 1, wherein the firstengaging part of the piston rod is a groove and the second engaging partof the handle is a protruding rib whereby the protruding rib is fixedlyinsertable in the groove.
 4. The air pump as claimed in claim 1, whereinthe handle is a T-shaped handle and has a transverse part and alongitudinal part, and the face of the handle is formed on an endsurface of the longitudinal part of the handle.
 5. The air pump asclaimed in claim 2, wherein the handle is a T-shaped handle and has atransverse part and a longitudinal part, and the face of the handle isformed on an end surface of the longitudinal part of the handle.
 6. Theair pump as claimed in claim 3, wherein the handle is a T-shaped handleand has a transverse part and a longitudinal part, and the face of thehandle is formed on an end surface of the longitudinal part of thehandle.
 7. The air pump as claimed in claim 1, wherein the handle iscylindrical and the face of the handle is formed on an end surface ofthe cylindrical handle.
 8. The air pump as claimed in claim 2, whereinthe handle is cylindrical and the face of the handle is formed on an endsurface of the cylindrical handle.
 9. The air pump as claimed in claim3, wherein the handle is cylindrical and the face of the handle isformed on an end surface of the cylindrical handle.
 10. The air pump asclaimed in claim 7, wherein the air pump has multiple slip-resistantribs and the slip-resistant ribs are formed around and protruding fromthe handle.
 11. The air pump as claimed in claim 8, wherein the air pumphas multiple slip-resistant ribs and the slip-resistant ribs are formedaround and protruding from the handle.
 12. The air pump as claimed inclaim 9, wherein the air pump has multiple slip-resistant ribs and theslip-resistant ribs are formed around and protruding from the handle.